The emission spectrum of the PH⁺ molecule

Abstract

A system of three red degraded bands at 3854, 4228, and 3567 Å has been obtained in emission from a hollow cathode discharge through helium containing a little phosphorus vapor and hydrogen. Rotational analyses of the bands show that they are the 0–0, 0–1, and 1–0 bands of a ²Δ-²Π transition of the PH⁺ molecule. The ²Δ state is regular with small spin splitting (case b) while the ²Π state is regular with large spin splitting (case a). For ν=0, the F₁ levels of the ²Δ state with N≥13 and the F₂ levels with N≥15 are predissociated. Also the lines arising from the F₁ levels of the ²Δ state with ν=1 are found to be extremely weak compared to those arising from the F₂ levels. Vibrational and rotational constants have been determined and the dissociation energy has been found to be 3.06±0.25 ev.